An internal combustion engine converts heat energy generated from combustion of the fuel into mechanical work by action on a piston, a turbine blade, and the like.
The internal combustion engine can be classified into a gas engine, a gasoline engine, a petroleum engine, a diesel engine, and the like, based on types of fuel.
For instance, the petroleum, gas, and gasoline engines are ignited by an electric spark from a spark plug, and the diesel engine sprays fuel into high temperature and high pressure air to spontaneously ignite.
The internal combustion engine also can be classified into a four stroke cycle engine and a two stroke cycle engine based on the stroke/movement of a piston.
The internal combustion engine of a vehicle is commonly known to have thermal efficiency of about 15% to 35%. However, even at the maximum efficiency of the internal combustion engine, about 60% or more of total heat energy may be dissipated as heat energy, exhaust gas, or the like is discharged to outside through the wall of the internal combustion engine.
If the amount of heat energy discharged outside through the wall of an internal combustion engine is reduced, internal combustion engine efficiency may be increased. Thus, studies have progressed on promoting thermal efficiency improvement by forming a heat insulation film of a material with low thermal conductivity on all the wall surfaces, such as top of a piston in a combustion chamber and a cylinder head, to decrease a heat transfer from fuel gas in the combustion chamber to the piston.
However, under the combustion environment of an internal combustion engine, exhaust gas temperature can rise up to a temperature of about 1600° C., the internal temperature of a combustion chamber reaches to about 600° C., and an internal pressure is substantially increased. Thus, high heat resistance and impact resistance may be required for the heat insulation film to be applied inside the internal combustion engine.
To overcome such a problem, a method of mixing a high heat resistant binder resin with low thermal conductivity and ultralow density aerogels with high heat resistance and impact resistance has been suggested to prepare a heat insulation film. Since the aerogel is mainly made of a silicon oxide, carbon, or organic polymer, and it has a porosity of about 90% or greater through a structure where microfilaments with a thickness of one ten thousandth of a hair width are entangled, it may have an excellent heat insulation property, high strength, and excellent sound proofing and impact absorbing properties. However, the heat capacity of the high heat resistant binder resin may not be reduced sufficiently to improve thermal efficiency of an internal combustion engine. Further, when the aerogels are added to the binder resin to decrease heat capacity, adherence of a heal insulation film may be reduced as the content of aerogels increases, and thus the amount of the aerogels is limited.
Therefore, there is a demand for development of a novel resin composition comprising the aerogel that has low volume heat capacity and low thermal conductivity to improve heat resistance.